1. Field of the Invention
The present invention relates generally to lighting device's structure, and more particularly to an illuminating apparatus which has a good thermal dissipation performance.
2. Description of the Related Art
Light emitting diode (LED) is widely used in the present days because of its small size, low power consumption, high efficiency, and long lifespan. FIG. 1 shows a conventional LED bulb 1, which includes a base 2, a metal core printed circuit board (MCPCB) 3 mounted on the base 2, a plurality of LEDs 4 on the MCPCB 3, and a cover 5 connected to the base 2 to cover and protect the LEDs 4. The conventional light bulbs are gradually replaced by the LED bulbs. However, the conventional LED bulb 1 still has the following drawbacks:
1. The size of the MCPCB 3 is limited by the cover 5, and therefore the LEDs 4 on the MCPCB 3 are very crowded, so that the conventional LED bulb 1 is very hot, and the heat is hard to dissipate. It will reduce the illumination efficiency and shorten the LED bulb's 1 life. The problem is even worse for a high lumens LED bulb.
2. Although the base 2 is made of aluminum, which is good at thermal dissipation, but the base 2 only has a very small area in touch with the MCPCB 3 and a dissipating surface 2a is far away from the MCPCB 3, so that the conventional LED bulb 1 only has poor thermal dissipation performance. Besides, the aluminum base 2 is very expensive.
3. The base 2 is opaque, and therefore the light of the LEDs 4 only comes out through the transparent cover 5. It limits the angle of illumination.